title: Assessing the effect of hormonal contraception on HIV acquisition in observational data: challenges and recommended analytic approaches.
abstract: BACKGROUND
  Determining whether hormonal contraception, particularly the injectable contraceptive depot-medroxyprogesterone acetate (DMPA), increases a woman's risk of HIV acquisition is a priority question for public health. However, assessing the relationship between various hormonal contraceptive methods and HIV acquisition with observational data involves substantial analytic design issues and challenges. Studies to date have used inconsistent approaches and generated a body of evidence that is complex and challenging to interpret.
  
  
  METHODS
  In January 2013, the United States Agency for International Development and FHI 360 supported a meeting of epidemiologists, statisticians, and content experts to develop recommendations for future observational analyses of hormonal contraception and HIV acquisition.
  
  
  RESULTS
  Meeting participants generated recommendations regarding careful definition of exposure groups; handling potential confounders, mediators, and effect modifiers; estimating and addressing the magnitude of measurement error; using multiple methods to account for pregnancy; and exploring the potential for differential exposure to HIV-infected partners. Advantages and disadvantages of various statistical approaches to account for time-varying confounding and estimating total and direct effects were also discussed.
  
  
  CONCLUSIONS
  Implementing these recommendations in future observational hormonal contraception-HIV acquisition analyses will enhance interpretation of existing studies and strengthen the overall evidence base for this complex and important area.
authors.affiliation: aOffice of Population and Reproductive Health, United States Agency for International Development (USAID), Washington, DC bDepartment of Epidemiology, University of North Carolina, Chapel Hill cDepartment of Obstetrics & Gynecology and Global Health Institute, Duke University, Durham, North Carolina dVaccine and Infectious Disease Division, Fred Hutchinson Cancer Research Center eDepartment of Global Health, University of Washington, Seattle, Washington, USA. *Chelsea B. Polis, Daniel Westreich, Jennifer E. Balkus and Renee Heffron contributed equally to the writing of the article.
authors.forename: Chelsea B
authors.initials: CB
authors.lastname: Polis
authors.forename: Daniel
authors.initials: D
authors.lastname: Westreich
authors.forename: Jennifer E
authors.initials: JE
authors.lastname: Balkus
authors.forename: Renee
authors.initials: R
authors.lastname: Heffron
mesh_terms: D035843:Biomedical Research / Q000379:methods*; D003271:Contraceptive Agents, Female / Q000008:administration & dosage*; D005260:Female; D017408:Guidelines as Topic; D015658:HIV Infections / Q000453:epidemiology* / Q000635:transmission*; D006801:Humans; D007267:Injections; D018570:Risk Assessment / Q000379:methods; D014481:United States
chemical_list: D003271:Contraceptive Agents, Female